Re: Difference between fully integration and reduced integration

aruk77500 <aruk77500 <at> yahoo.com>
2009-11-14 13:30:28 GMT

It is about numerical integration. The ingetral for evaluating for example stiffness matrix is carried along finite elements. These integrals are approximated with sum of some calculated values at specific points, which are gauss points, through the elements. more the gauss points, more accurate your calculations will be. reduced integration elements have only one integration point while in full integration, there are four integration points. the stress results are calculated and output at these integration points and then extrapolated to other poitns by means of shape functions.

the problem with full integration elements is shear locking, while the problem with reduced integration elements is hour-glass modes. there are specially formulated elements in abaqus for hour glassing, which is activated via element type selection tool in abaqus CAE. reduced integration elements in abaqus are cheaper and they are default element types I think.

Re: Difference between fully integration and reduced integration

Ranil Banneyake <ranilb5 <at> gmail.com>
2009-11-15 00:34:10 GMT

HI Prasad,

It is about the accuracy of the integration used in stiffness matrix
formulation. Various integration rules (known as 'Gauss Quadrature Rules' )
of varying accuracy are used, and the number of associated integration
points (Gauss points) changes accordingly. In case of full integration all
the stiffness coefficients of an un-distorted elementscan be exactly
integrated. When we omit hihger order terms (i.e. reduce integration) only
some can be integrated exactly. However, required computational resources
will be less.

If you use first order elements with full-integration since they capture
bedning with shear like distortion in the element, full-integration elements
tend to be stiffer for bending. With reduced integration this can be
overcome but it can have hourglass effect when bending producing less
bending resistane.